As Motherboard reports, some users have been publicly wondering why their timelines are out of order. In a statement, Twitter confirmed that those users are part of an experiment. “We’re continuing to explore ways to surface the best content for people using Twitter,” the company said.

Breaking chronology isn’t entirely new for Twitter. In January, the social network introduced recaps in its mobile apps, showing popular tweets that users might not have seen in their timelines earlier. But these summaries, which appear under a “While you were away” heading, can be dismissed if users want to jump straight to reverse-chronological order.

The latest experiment appears to remove chronology outright. The approach is similar to that of Facebook, which users algorithms to decide what appears at the top of users’ news feeds. (Notably, Facebook still offers an option to see most recent posts first, and has also added a way to move favorite people to the top of the feed.)

Chronology aside, Twitter has been inviting plenty of comparisons to Facebook lately. Last month, the network ditched “favorites” (marked with a star) for “likes,” represented by hearts. Twitter has also added more media—including looping videos and interactive polls—directly into users’ timelines, and is reportedly considering ways to expand beyond its 140-character text limit. But reshuffling users’ timelines, if it ever became more than an experiment, would be Twitter’s most drastic change yet.

The story behind the story: The trial comes amid a period of big changes and soul-searching at Twitter. The company recently laid off 8 percent of its workforce, with new CEO (and co-founder) Jack Dorsey saying the goal was to improve focus and reinvest in growth. Twitter has struggled in recent years to attract and retain users, so it’s understandable that the company would try things that previously seemed off-limits. The challenge is to do so in a way that doesn’t alienate the users who are generating all the content.